Determining surface current direction while in DP

**Capt.Mac** · December 15th, 2009, 01:36 PM

I am a new DPO Jr. and wondered if you might offer a tip on determining surface current direction. Currently I am using F/A, P/S and heading integrals to come up with a rough idea of direction. Is there a more precise method than this?
Thanks for your help.

**richard8000milesaway** · December 15th, 2009, 02:51 PM

reminder: the (correct) information you are using to calculate will only give you the "unknown" forces acting on the vessel & these will collectively be termed "current" by the computer. if you REALLY want to know what the actual surface current is you'll have to fall back on your seamanship training: set & drift calculations, visual estimates, etc.

**Capt.Mac** · December 16th, 2009, 04:30 PM

True enough when underway, but when on DP and holding position determining set and drift is not feasible is it? Thanks for the come back

**richard8000milesaway** · January 8th, 2010, 05:47 PM

sorry for the delayed response. can we blame it on me being in africa? sure.

actually, yes, you can get a pretty good idea of current any time offshore even on DP: a look out over the side from the bridge wing on a motionless vessel will give you a good accuracy with a little practice if the currents are more then 1 knot (look for these floating items to drift by: weed, white cuttlefish chalk, any natural sorts of stuff, as long as it has NO WIND AREA and is submerged it will tell you current direction and speed with practice. take your time. 5 minutes or so. watch and watch. the ocean surface will tell you lots if you have patience.)

the best way to practice is to always look up your current on your DP then go out and look for a while at the water surface to see what it looks like (bearing is easy speed calc takes practice). if you do this a lot you'll get better at it and soon you'll be pretty good so when the sh#t hits the fan you'll be able to work without any tools other then your eyes. of course, you may find yourself - hopefully - making this part of your hourly watch routine. needless to say you should be doing this with your radar & ECIDS as well: the time to learn how to live without a favortie tool is NOT when that tool has broken.....

Some jackass DPO's will do a "drift test" and just let the vessel drift for an hour or so before going on DP thinking that is the true current, but we know they're wrong... right? right? Bueller? Bueller? hope so. that is a basic principal of DP.